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	<title>DataTables example - Pipelining data to reduce Ajax calls for paging</title>
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//
// Pipelining function for DataTables. To be used to the `ajax` option of DataTables
//
$.fn.dataTable.pipeline = function ( opts ) {
	// Configuration options
	var conf = $.extend( {
		pages: 5,     // number of pages to cache
		url: '',      // script url
		data: null,   // function or object with parameters to send to the server
		              // matching how `ajax.data` works in DataTables
		method: 'GET' // Ajax HTTP method
	}, opts );

	// Private variables for storing the cache
	var cacheLower = -1;
	var cacheUpper = null;
	var cacheLastRequest = null;
	var cacheLastJson = null;

	return function ( request, drawCallback, settings ) {
		var ajax          = false;
		var requestStart  = request.start;
		var requestLength = request.length;
		var requestEnd    = requestStart + requestLength;
		
		if ( settings.clearCache ) {
			// API requested that the cache be cleared
			ajax = true;
			settings.clearCache = false;
		}
		else if ( cacheLower < 0 || requestStart < cacheLower || requestEnd > cacheUpper ) {
			// outside cached data - need to make a request
			ajax = true;
		}
		else if ( JSON.stringify( request.order )   !== JSON.stringify( cacheLastRequest.order ) ||
		          JSON.stringify( request.columns ) !== JSON.stringify( cacheLastRequest.columns ) ||
		          JSON.stringify( request.search )  !== JSON.stringify( cacheLastRequest.search )
		) {
			// properties changed (ordering, columns, searching)
			ajax = true;
		}
		
		// Store the request for checking next time around
		cacheLastRequest = $.extend( true, {}, request );

		if ( ajax ) {
			// Need data from the server
			if ( requestStart < cacheLower ) {
				requestStart = requestStart - (requestLength*(conf.pages-1));

				if ( requestStart < 0 ) {
					requestStart = 0;
				}
			}
			
			cacheLower = requestStart;
			cacheUpper = requestStart + (requestLength * conf.pages);

			request.start = requestStart;
			request.length = requestLength*conf.pages;

			// Provide the same `data` options as DataTables.
			if ( $.isFunction ( conf.data ) ) {
				// As a function it is executed with the data object as an arg
				// for manipulation. If an object is returned, it is used as the
				// data object to submit
				var d = conf.data( request );
				if ( d ) {
					$.extend( request, d );
				}
			}
			else if ( $.isPlainObject( conf.data ) ) {
				// As an object, the data given extends the default
				$.extend( request, conf.data );
			}

			settings.jqXHR = $.ajax( {
				"type":     conf.method,
				"url":      conf.url,
				"data":     request,
				"dataType": "json",
				"cache":    false,
				"success":  function ( json ) {
					cacheLastJson = $.extend(true, {}, json);

					if ( cacheLower != requestStart ) {
						json.data.splice( 0, requestStart-cacheLower );
					}
					json.data.splice( requestLength, json.data.length );
					
					drawCallback( json );
				}
			} );
		}
		else {
			json = $.extend( true, {}, cacheLastJson );
			json.draw = request.draw; // Update the echo for each response
			json.data.splice( 0, requestStart-cacheLower );
			json.data.splice( requestLength, json.data.length );

			drawCallback(json);
		}
	}
};

// Register an API method that will empty the pipelined data, forcing an Ajax
// fetch on the next draw (i.e. `table.clearPipeline().draw()`)
$.fn.dataTable.Api.register( 'clearPipeline()', function () {
	return this.iterator( 'table', function ( settings ) {
		settings.clearCache = true;
	} );
} );


//
// DataTables initialisation
//
$(document).ready(function() {
	$('#example').dataTable( {
		"processing": true,
		"serverSide": true,
		"ajax": $.fn.dataTable.pipeline( {
			url: 'scripts/server_processing.php',
			pages: 5 // number of pages to cache
		} )
	} );
} );


	</script>
</head>

<body class="dt-example">
	<div class="container">
		<section>
			<h1>DataTables example <span>Pipelining data to reduce Ajax calls for paging</span></h1>

			<div class="info">
				<p>Sever-side processing can be quite hard on your server, since it makes an Ajax call to the server
				for every draw request that is made. On sites with a large number of page views, you could potentially
				end up DDoSing your own server with your own applications!</p>

				<p>This example shows one technique to reduce the number of Ajax calls that are made to the server by
				caching more data than is needed for each draw. This is done by intercepting the Ajax call and routing
				it through a data cache control; using the data from the cache if available, and making the Ajax
				request if not. This intercept of the Ajax request is performed by giving the <a href=
				"//datatables.net/reference/option/ajax"><code class="option" title=
				"DataTables initialisation option">ajax<span>DT</span></code></a> option as a function. This function
				then performs the logic of deciding if another Ajax call is needed, or if data from the cache can be
				used.</p>

				<p>Keep in mind that this caching is for paging only; the pipeline must be cleared for other
				interactions such as ordering and searching since the full data set, when using server-side processing,
				is only available at the server.</p>
			</div>

			<table id="example" class="display" cellspacing="0" width="100%">
				<thead>
					<tr>
						<th>Name</th>
						<th>Position</th>
						<th>Office</th>
						<th>Extn.</th>
						<th>Start date</th>
						<th>Salary</th>
					</tr>
				</thead>

				<tfoot>
					<tr>
						<th>Name</th>
						<th>Position</th>
						<th>Office</th>
						<th>Extn.</th>
						<th>Start date</th>
						<th>Salary</th>
					</tr>
				</tfoot>
			</table>

			<ul class="tabs">
				<li class="active">Javascript</li>
				<li>HTML</li>
				<li>CSS</li>
				<li>Ajax</li>
				<li>Server-side script</li>
			</ul>

			<div class="tabs">
				<div class="js">
					<p>The Javascript shown below is used to initialise the table shown in this
					example:</p><code class="multiline brush: js;">//
// Pipelining function for DataTables. To be used to the `ajax` option of DataTables
//
$.fn.dataTable.pipeline = function ( opts ) {
	// Configuration options
	var conf = $.extend( {
		pages: 5,     // number of pages to cache
		url: '',      // script url
		data: null,   // function or object with parameters to send to the server
		              // matching how `ajax.data` works in DataTables
		method: 'GET' // Ajax HTTP method
	}, opts );

	// Private variables for storing the cache
	var cacheLower = -1;
	var cacheUpper = null;
	var cacheLastRequest = null;
	var cacheLastJson = null;

	return function ( request, drawCallback, settings ) {
		var ajax          = false;
		var requestStart  = request.start;
		var requestLength = request.length;
		var requestEnd    = requestStart + requestLength;
		
		if ( settings.clearCache ) {
			// API requested that the cache be cleared
			ajax = true;
			settings.clearCache = false;
		}
		else if ( cacheLower &lt; 0 || requestStart &lt; cacheLower || requestEnd &gt; cacheUpper ) {
			// outside cached data - need to make a request
			ajax = true;
		}
		else if ( JSON.stringify( request.order )   !== JSON.stringify( cacheLastRequest.order ) ||
		          JSON.stringify( request.columns ) !== JSON.stringify( cacheLastRequest.columns ) ||
		          JSON.stringify( request.search )  !== JSON.stringify( cacheLastRequest.search )
		) {
			// properties changed (ordering, columns, searching)
			ajax = true;
		}
		
		// Store the request for checking next time around
		cacheLastRequest = $.extend( true, {}, request );

		if ( ajax ) {
			// Need data from the server
			if ( requestStart &lt; cacheLower ) {
				requestStart = requestStart - (requestLength*(conf.pages-1));

				if ( requestStart &lt; 0 ) {
					requestStart = 0;
				}
			}
			
			cacheLower = requestStart;
			cacheUpper = requestStart + (requestLength * conf.pages);

			request.start = requestStart;
			request.length = requestLength*conf.pages;

			// Provide the same `data` options as DataTables.
			if ( $.isFunction ( conf.data ) ) {
				// As a function it is executed with the data object as an arg
				// for manipulation. If an object is returned, it is used as the
				// data object to submit
				var d = conf.data( request );
				if ( d ) {
					$.extend( request, d );
				}
			}
			else if ( $.isPlainObject( conf.data ) ) {
				// As an object, the data given extends the default
				$.extend( request, conf.data );
			}

			settings.jqXHR = $.ajax( {
				&quot;type&quot;:     conf.method,
				&quot;url&quot;:      conf.url,
				&quot;data&quot;:     request,
				&quot;dataType&quot;: &quot;json&quot;,
				&quot;cache&quot;:    false,
				&quot;success&quot;:  function ( json ) {
					cacheLastJson = $.extend(true, {}, json);

					if ( cacheLower != requestStart ) {
						json.data.splice( 0, requestStart-cacheLower );
					}
					json.data.splice( requestLength, json.data.length );
					
					drawCallback( json );
				}
			} );
		}
		else {
			json = $.extend( true, {}, cacheLastJson );
			json.draw = request.draw; // Update the echo for each response
			json.data.splice( 0, requestStart-cacheLower );
			json.data.splice( requestLength, json.data.length );

			drawCallback(json);
		}
	}
};

// Register an API method that will empty the pipelined data, forcing an Ajax
// fetch on the next draw (i.e. `table.clearPipeline().draw()`)
$.fn.dataTable.Api.register( 'clearPipeline()', function () {
	return this.iterator( 'table', function ( settings ) {
		settings.clearCache = true;
	} );
} );


//
// DataTables initialisation
//
$(document).ready(function() {
	$('#example').dataTable( {
		&quot;processing&quot;: true,
		&quot;serverSide&quot;: true,
		&quot;ajax&quot;: $.fn.dataTable.pipeline( {
			url: 'scripts/server_processing.php',
			pages: 5 // number of pages to cache
		} )
	} );
} );</code>

					<p>In addition to the above code, the following Javascript library files are loaded for use in this
					example:</p>

					<ul>
						<li><a href="../../media/js/jquery.js">../../media/js/jquery.js</a></li>
						<li><a href="../../media/js/jquery.dataTables.js">../../media/js/jquery.dataTables.js</a></li>
					</ul>
				</div>

				<div class="table">
					<p>The HTML shown below is the raw HTML table element, before it has been enhanced by
					DataTables:</p>
				</div>

				<div class="css">
					<div>
						<p>This example uses a little bit of additional CSS beyond what is loaded from the library
						files (below), in order to correctly display the table. The additional CSS used is shown
						below:</p><code class="multiline brush: js;"></code>
					</div>

					<p>The following CSS library files are loaded for use in this example to provide the styling of the
					table:</p>

					<ul>
						<li><a href=
						"../../media/css/jquery.dataTables.css">../../media/css/jquery.dataTables.css</a></li>
					</ul>
				</div>

				<div class="ajax">
					<p>This table loads data by Ajax. The latest data that has been loaded is shown below. This data
					will update automatically as any additional data is loaded.</p>
				</div>

				<div class="php">
					<p>The script used to perform the server-side processing for this table is shown below. Please note
					that this is just an example script using PHP. Server-side processing scripts can be written in any
					language, using <a href="//datatables.net/manual/server-side">the protocol described in the
					DataTables documentation</a>.</p>
				</div>
			</div>
		</section>
	</div>

	<section>
		<div class="footer">
			<div class="gradient"></div>

			<div class="liner">
				<h2>Other examples</h2>

				<div class="toc">
					<div class="toc-group">
						<h3><a href="../basic_init/index.html">Basic initialisation</a></h3>
						<ul class="toc">
							<li><a href="../basic_init/zero_configuration.html">Zero configuration</a></li>
							<li><a href="../basic_init/filter_only.html">Feature enable / disable</a></li>
							<li><a href="../basic_init/table_sorting.html">Default ordering (sorting)</a></li>
							<li><a href="../basic_init/multi_col_sort.html">Multi-column ordering</a></li>
							<li><a href="../basic_init/multiple_tables.html">Multiple tables</a></li>
							<li><a href="../basic_init/hidden_columns.html">Hidden columns</a></li>
							<li><a href="../basic_init/complex_header.html">Complex headers (rowspan and
							colspan)</a></li>
							<li><a href="../basic_init/dom.html">DOM positioning</a></li>
							<li><a href="../basic_init/flexible_width.html">Flexible table width</a></li>
							<li><a href="../basic_init/state_save.html">State saving</a></li>
							<li><a href="../basic_init/alt_pagination.html">Alternative pagination</a></li>
							<li><a href="../basic_init/scroll_y.html">Scroll - vertical</a></li>
							<li><a href="../basic_init/scroll_x.html">Scroll - horizontal</a></li>
							<li><a href="../basic_init/scroll_xy.html">Scroll - horizontal and vertical</a></li>
							<li><a href="../basic_init/scroll_y_theme.html">Scroll - vertical with jQuery UI
							ThemeRoller</a></li>
							<li><a href="../basic_init/comma-decimal.html">Language - Comma decimal place</a></li>
							<li><a href="../basic_init/language.html">Language options</a></li>
						</ul>
					</div>

					<div class="toc-group">
						<h3><a href="../advanced_init/index.html">Advanced initialisation</a></h3>
						<ul class="toc">
							<li><a href="../advanced_init/events_live.html">DOM / jQuery events</a></li>
							<li><a href="../advanced_init/dt_events.html">DataTables events</a></li>
							<li><a href="../advanced_init/column_render.html">Column rendering</a></li>
							<li><a href="../advanced_init/length_menu.html">Page length options</a></li>
							<li><a href="../advanced_init/dom_multiple_elements.html">Multiple table control
							elements</a></li>
							<li><a href="../advanced_init/complex_header.html">Complex headers (rowspan /
							colspan)</a></li>
							<li><a href="../advanced_init/html5-data-attributes.html">HTML5 data-* attributes</a></li>
							<li><a href="../advanced_init/language_file.html">Language file</a></li>
							<li><a href="../advanced_init/defaults.html">Setting defaults</a></li>
							<li><a href="../advanced_init/row_callback.html">Row created callback</a></li>
							<li><a href="../advanced_init/row_grouping.html">Row grouping</a></li>
							<li><a href="../advanced_init/footer_callback.html">Footer callback</a></li>
							<li><a href="../advanced_init/dom_toolbar.html">Custom toolbar elements</a></li>
							<li><a href="../advanced_init/sort_direction_control.html">Order direction sequence
							control</a></li>
						</ul>
					</div>

					<div class="toc-group">
						<h3><a href="../styling/index.html">Styling</a></h3>
						<ul class="toc">
							<li><a href="../styling/display.html">Base style</a></li>
							<li><a href="../styling/no-classes.html">Base style - no styling classes</a></li>
							<li><a href="../styling/row-border.html">Base style - row borders</a></li>
							<li><a href="../styling/cell-border.html">Base style - cell borders</a></li>
							<li><a href="../styling/hover.html">Base style - hover</a></li>
							<li><a href="../styling/order-column.html">Base style - order-column</a></li>
							<li><a href="../styling/stripe.html">Base style - stripe</a></li>
							<li><a href="../styling/jqueryUI.html">jQuery UI ThemeRoller</a></li>
							<li><a href="../styling/bootstrap.html">Bootstrap</a></li>
							<li><a href="../styling/foundation.html">Foundation</a></li>
						</ul>
					</div>

					<div class="toc-group">
						<h3><a href="../data_sources/index.html">Data sources</a></h3>
						<ul class="toc">
							<li><a href="../data_sources/dom.html">HTML (DOM) sourced data</a></li>
							<li><a href="../data_sources/ajax.html">Ajax sourced data</a></li>
							<li><a href="../data_sources/js_array.html">Javascript sourced data</a></li>
							<li><a href="../data_sources/server_side.html">Server-side processing</a></li>
						</ul>
					</div>

					<div class="toc-group">
						<h3><a href="../api/index.html">API</a></h3>
						<ul class="toc">
							<li><a href="../api/add_row.html">Add rows</a></li>
							<li><a href="../api/multi_filter.html">Individual column filtering (text inputs)</a></li>
							<li><a href="../api/multi_filter_select.html">Individual column filtering (select
							inputs)</a></li>
							<li><a href="../api/highlight.html">Highlighting rows and columns</a></li>
							<li><a href="../api/row_details.html">Child rows (show extra / detailed
							information)</a></li>
							<li><a href="../api/select_row.html">Row selection (multiple rows)</a></li>
							<li><a href="../api/select_single_row.html">Row selection and deletion (single
							row)</a></li>
							<li><a href="../api/form.html">Form inputs</a></li>
							<li><a href="../api/counter_columns.html">Index column</a></li>
							<li><a href="../api/show_hide.html">Show / hide columns dynamically</a></li>
							<li><a href="../api/api_in_init.html">Using API in callbacks</a></li>
							<li><a href="../api/tabs_and_scrolling.html">Scrolling and jQuery UI tabs</a></li>
							<li><a href="../api/regex.html">Filtering API (regular expressions)</a></li>
						</ul>
					</div>

					<div class="toc-group">
						<h3><a href="../ajax/index.html">Ajax</a></h3>
						<ul class="toc">
							<li><a href="../ajax/simple.html">Ajax data source (arrays)</a></li>
							<li><a href="../ajax/objects.html">Ajax data source (objects)</a></li>
							<li><a href="../ajax/deep.html">Nested object data (objects)</a></li>
							<li><a href="../ajax/objects_subarrays.html">Nested object data (arrays)</a></li>
							<li><a href="../ajax/orthogonal-data.html">Orthogonal data</a></li>
							<li><a href="../ajax/null_data_source.html">Generated content for a column</a></li>
							<li><a href="../ajax/custom_data_property.html">Custom data source property</a></li>
							<li><a href="../ajax/custom_data_flat.html">Flat array data source</a></li>
							<li><a href="../ajax/defer_render.html">Deferred rendering for speed</a></li>
						</ul>
					</div>

					<div class="toc-group">
						<h3><a href="./index.html">Server-side</a></h3>
						<ul class="toc active">
							<li><a href="./simple.html">Server-side processing</a></li>
							<li><a href="./custom_vars.html">Custom HTTP variables</a></li>
							<li><a href="./post.html">POST data</a></li>
							<li><a href="./ids.html">Automatic addition of row ID attributes</a></li>
							<li><a href="./object_data.html">Object data source</a></li>
							<li><a href="./row_details.html">Row details</a></li>
							<li><a href="./select_rows.html">Row selection</a></li>
							<li><a href="./jsonp.html">JSONP data source for remote domains</a></li>
							<li><a href="./defer_loading.html">Deferred loading of data</a></li>
							<li class="active"><a href="./pipeline.html">Pipelining data to reduce Ajax calls for
							paging</a></li>
						</ul>
					</div>

					<div class="toc-group">
						<h3><a href="../plug-ins/index.html">Plug-ins</a></h3>
						<ul class="toc">
							<li><a href="../plug-ins/api.html">API plug-in methods</a></li>
							<li><a href="../plug-ins/sorting_auto.html">Ordering plug-ins (with type
							detection)</a></li>
							<li><a href="../plug-ins/sorting_manual.html">Ordering plug-ins (no type
							detection)</a></li>
							<li><a href="../plug-ins/range_filtering.html">Custom filtering - range search</a></li>
							<li><a href="../plug-ins/dom_sort.html">Live DOM ordering</a></li>
						</ul>
					</div>
				</div>

				<div class="epilogue">
					<p>Please refer to the <a href="http://www.datatables.net">DataTables documentation</a> for full
					information about its API properties and methods.<br>
					Additionally, there are a wide range of <a href="http://www.datatables.net/extras">extras</a> and
					<a href="http://www.datatables.net/plug-ins">plug-ins</a> which extend the capabilities of
					DataTables.</p>

					<p class="copyright">DataTables designed and created by <a href=
					"http://www.sprymedia.co.uk">SpryMedia Ltd</a> &#169; 2007-2014<br>
					DataTables is licensed under the <a href="http://www.datatables.net/mit">MIT license</a>.</p>
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